Wireless Set No. 52 Canadian - Project

[David Dunlop]

This is quite an impressive wiring harness when you finally see it out of the 52-Set Receiver chassis. The perimeter rectangle for it in the photograph is 16 inches by 24 inches, and it would have been a very interesting workstation on the production line to watch in action.

I wonder how many of these harness looms would have been assembled in any given work shift?


David

[David Dunlop]

This is the only other free standing wiring harness in the 52-Set Receiver. In the photo, it sits within a 9-inch square.

It is found on the lower left front of the chassis, connecting the A.F. GAIN, NOISE LIMITER IN/OUT and HET. TONE Switches to their relevant circuits on the back and bottom of the chassis.


David

[David Dunlop]

This particular switch in the 52-Set Receiver wins the award for the longest switch shaft.

Its location on the underside of the chassis can be seen in the first photos of both Post #619 and Post #620 .The terminal wafer assembly on the switch is located at the back of the lower chassis, supported in place by a mounting plate that forms a part of the frame for the switch. The holes in the lower front of the chassis and lower front panel plate support the front end of the shaft. Total length of the shaft is 9-1/4 inches.

This is the SHARP FLAT Switch in the receiver circuits.


David

[David Dunlop]

This is the shorter relative of its 5.5-inch cousin I covered in Post #617 and is of identical construction. In fact, it is the description of this CONNECTIONS, Screened that confirms how both are put together such that the wire does not make contact internally with the tube.

An appropriate length of the tinned, solid copper wire is cut and a small bead of solder applied at the required distance in from one end and a ceramic end cap dropped in place down the wire. Ceramic fish beads are then added down the wire in sufficient number to fill the metal tube. This wire and bead string is then slid into one end of the tube and pulled into place. The ceramic end cap is added to the open end of the string and a small bead of solder added at that end to secure and complete the assembly. The ceramic fish beads inside the tube are small enough let the wire down the middle of them flex with the curve of the tube, yet stay centred in the tube.

In the second photo of POST #619, you can see this CONNECTIONS, Screened tucked in between the two long rectangular banks of coil/caps, at the right hand side of the gap.

David

[David Dunlop]

The next phase of this parts receiver disassembly is going to focus on the removal of the 3-Gang Tuning Capacitor and the Coils Assembly, RF, mounted directly above it. These two units take up most of the right front half of the receiver. I still have a few bits to think through before I forge ahead.

If you refer back once again to the 2nd Photo in Post #619, this is a view of the back of the receiver chassis, with the chassis resting on its left side. The upper centre section, with the nine evenly spaced access holes is the back of the COILS ASSEMBLY. The back end of the 3-Gang Tuning Capacitor, with its curved top and big splotch of red paint, sits directly to the left of the Coils Assembly. Three leads from the Coils Assembly still run to the V1A, B and C sockets to the right side of the photo. These leads need to be unsoldered from their valve socket terminals.

The photo attached today shows these two components from the front of the receiver chassis. From what I can see so far, there are five leads running from the lower Tuning Capacitor up into the Coils Assembly. All these appear to be solid wire leads and may prove a bit tricky to get at with a soldering iron. Then there is the need to track down where all the mounting hardware is and sort out its removal.

You will notice in the attached photo, the INDUCTANCES, RF (L10A) is mounted to the bottom section of the Coils Assembly and actually extends down, in front of the Tuning Capacitor. This is the large disc, roughly centered on the Coils Assembly. This means the Tuning Capacitor had to be installed on the chassis before the Coils Assembly went on. Interesting.

On the front of the finished receiver, L10A shows up as the FREQ. ADJ. Knob.


David

[David Dunlop]

My observations about the number of leads feeding up from the Tuning Capacitor below the COIL ASSEMBLIES proved correct. There were five of them: one coming out the left (inner) side of the Tuning Capacitor and four feeding up through the right hand side of the Tuning Capacitor cover, through small, metal sleeved holes. A bit of a challenge to get at with a soldering iron, but more on that later.

The mounting hardware for the Coil Assemblies is fairly comprehensive, involving 11 sets in total.

On the left side, there are three slot head, countersunk, machine screws. The two upper ones utilize hex nuts and external tooth lock washers on the inside of the receiver chassis wall to secure them. The 3rd screw simply fastens directly into the end of the front support rod assembly of the Coil Assembly. This rod is a three section affair and access to fit an external tooth lock washer on the interior of the left receiver chassis wall is none existent, so to prevent the support rod section at the end from unscrewing when the outer screw is removed, an external toothed lock washer was added to the left end of this outer rod section, between the rod end and the right partition wall of the Coil Assembly.

On the vertical, right rear lip of the Coil Assembly, three holes are provided which drop over three threaded studs fitted down the inner wall of the receiver chassis. With the Coil Assembles in place, three hex nuts and external tooth lock washers hold it in place.

The top, horizontal, left rear lip of the Coil Assemblies fits directly against the rear wall of the receiver chassis and a pair of round head SEMS Fasteners with external tooth lock washers goes there.

The vertical lip down the left rear side of the Coil Assemblies also has provision for three more round head SEMS fasteners and external tooth lock washers.

My approach was to remove all the hardware except the two SEMS fasteners on the top left rear lip first. Then it was easy to support the Coil Assemblies with one hand while removing the last two screws.

The Coil Assemblies is an interesting component when you get it out of the receiver chassis, for a closer inspection. In situ, and looking at it from the front of the receiver, it is clear it is built in three distinct, shielded columns. Each directly under the following Valves, from left to right: V1C Mixer, V1B Conversion Oscillator and V1A the RF Amplifier.

When you start looking at the Coil Assembly more closely, and pay a little more attention to the components identified on the back of it, you realize the three coils in each column, along with their supporting capacitors, are also laid out in a horizontal pattern of three distinct rows. The top row deals with Band 3, 7.0 to 16 MC’s. The middle row deals with Band 2, 3.5 to 8.0 MC’s and the lower row relates to Band 1, 1.7 to 4.0 MC’s.

Combining the Valves and their basic functions, along with the three columns of the Coils Assemblies, the arm waving functions of each column in relation to the Valve(s) it is linked to can be summarized as follows:

The left column is the RF Amplifier Coupling between V1A and V1C, working primarily with Valve V1C, the Mixer.

The middle column is the RF Oscillator working with Valve V1B, the Conversion Oscillator.

The right column is the Aerial Coupling working with V1A, the RF Amplifier. In the last photo posted today, you can see a long wire, with a red and yellow tracer, arcing towards the camera on the left side. This is the output lead that came from the Crystal Calibrator and travelled through the long shielding tube mounted directly above Valves V1C, B and A. The shadow of the tube is visible on the chassis back wall in the photo in the previous Post #635. This lead feeds directly into this right side column of the Coil Assemblies.

I am hoping nothing serious needs repairing on my main set receiver Coil Assemblies. It would be a very challenging component to work on, even by its own on the workbench.


David

[David Dunlop]

The other interesting discovery regarding the Coil Assemblies, RF, was that it was also considered a major sub- assembly of the Receiver by Canadian Marconi Company.

Along the top end of the left side mounting strip of the Coil Assembly another Production/ Control Number was found, as per the attached photo, this number shows as, ‘#6247’.

It is hard to see this number when looking at a fully occupied receiver chassis from the front because the mounting for the Band Switch gearbox blocks a direct view. Then factor in if one was not aware of the existence of this number, one would not be looking for it anyway.

So it seems that as far as the Wireless Set No, 52 Receiver is concerned, the receiver chassis, Crystal Calibrator chassis and the Coil Assemblies, RF chassis all had Control Numbers assigned to them during the production process.


David